fix 'Alias for field number X' problem with NamedTuples (#527)

* fix 'Alias for field number X' problem with NamedTuples

* TST: Add test for duplicated attrs w/ namedtuples.

* TST: Add test of explicitly documented namedtuple params.

---------

Co-authored-by: Ross Barnowski <rossbar@berkeley.edu>

numpydoc/docscrape.py

@@ -706,6 +706,7 @@ def properties(self):
             for name, func in inspect.getmembers(self._cls)
             if (
                 not name.startswith("_")
+                and not self._should_skip_member(name, self._cls)
                 and (
                     func is None
                     or isinstance(func, (property, cached_property))
@@ -715,6 +716,19 @@ def properties(self):
             )
         ]
 
+    @staticmethod
+    def _should_skip_member(name, klass):
+        if (
+            # Namedtuples should skip everything in their ._fields as the
+            # docstrings for each of the members is: "Alias for field number X"
+            issubclass(klass, tuple)
+            and hasattr(klass, "_asdict")
+            and hasattr(klass, "_fields")
+            and name in klass._fields
+        ):
+            return True
+        return False
+
     def _is_show_member(self, name):
         if self.show_inherited_members:
             return True  # show all class members

numpydoc/tests/test_docscrape.py

@@ -1641,6 +1641,63 @@ def val(self):
     assert class_docstring["Attributes"][0].name == "val"
 
 
+def test_namedtuple_no_duplicate_attributes():
+    """
+    Ensure that attributes of namedtuples are not duplicated in the docstring.
+
+    See gh-257
+    """
+    from collections import namedtuple
+
+    foo = namedtuple("Foo", ("bar", "baz"))
+
+    # Create the SphinxClassDoc object via get_doc_object
+    sds = get_doc_object(foo)
+    assert sds["Attributes"] == []
+
+
+def test_namedtuple_class_docstring():
+    """Ensure that class docstring is preserved when inheriting from namedtuple.
+
+    See gh-257
+    """
+    from collections import namedtuple
+
+    foo = namedtuple("Foo", ("bar", "baz"))
+
+    class MyFoo(foo):
+        """MyFoo's class docstring"""
+
+    # Create the SphinxClassDoc object via get_doc_object
+    sds = get_doc_object(MyFoo)
+    assert sds["Summary"] == ["MyFoo's class docstring"]
+
+    # Example dataclass where constructor params are documented explicit.
+    # Parameter names/descriptions should be included in the docstring, but
+    # should not result in a duplicated `Attributes` section
+    class MyFooWithParams(foo):
+        """
+        MyFoo's class docstring
+
+        Parameters
+        ----------
+        bar : str
+           The bar attribute
+        baz : str
+           The baz attribute
+        """
+
+        bar: str
+        baz: str
+
+    sds = get_doc_object(MyFooWithParams)
+    assert "MyFoo's class docstring" in sds["Summary"]
+    assert len(sds["Attributes"]) == 0
+    assert len(sds["Parameters"]) == 2
+    assert sds["Parameters"][0].desc[0] == "The bar attribute"
+    assert sds["Parameters"][1].desc[0] == "The baz attribute"
+
+
 if __name__ == "__main__":
     import pytest